October Birthstone: Opal coffer for the born
In the realm of gemstones, opals have long been revered for their unique play-of-color and stunning beauty. From ancient civilisations to modern-day jewellery enthusiasts, these mesmerising stones have captured hearts and imaginations for centuries. However, with the advent of synthetic opals, understanding the differences between natural and lab-grown varieties has become essential.
### History of Opals
Natural opals, prized for their captivating play-of-color, have been cherished for millennia. Synthetic opals, on the other hand, were developed in laboratories to mimic their natural counterparts, allowing faster production and greater accessibility while replicating the core chemical and optical properties of natural opals.
### Types of Opals
**Natural Opals**: Formed underground over millions of years, natural opals come mainly from regions such as Australia (notably Lightning Ridge for black opals) and Ethiopia (Welo opals), renowned for their vibrant colors and varying water content.
**Synthetic Opals**: Lab-grown opals with accelerated formation, synthetic opals visually imitate natural opals but have distinct microscopic features.
**Doublets and Triplets**: Composite stones where thin slices of natural opal are glued to a backing and capped with quartz or glass, these offer an affordable option but have minimal resale value.
### Care for Opals
Natural opals, especially hydrophane types like Ethiopian opals, are porous and sensitive to moisture and rapid temperature changes. They require gentle handling to avoid cracking. Avoid harsh chemicals, sudden temperature shifts, and prolonged water exposure. Store opals in a padded, humidity-controlled environment to maintain stability and prevent dehydration or brittleness. Synthetic opals generally share similar care needs but may be slightly less sensitive due to their controlled creation process.
### How to Differentiate Synthetic and Natural Opals When Purchasing
To ensure you're purchasing a natural opal, several tests can be carried out:
- **Phosphorescence Test**: Natural Australian sedimentary opals exhibit phosphorescence—glowing briefly after UV light is turned off—whereas synthetic opals do not phosphoresce. - **Pattern Observation Under Magnification**: Synthetic opals often show a mosaic, cellular, or "chicken wire" pattern distinct from natural opal's natural play of color patterns. - **Physical Feel & Structure**: Synthetic opals may feel plastic-like, and synthetic white opals can exhibit columnar internal structures when viewed from the side. - **Stick to Tongue Test**: Some synthetic opals may stick slightly to the tongue, unlike natural ones. - **Look for Composite Signs**: Doublets/triplets often have a distinct flat line between layers, glassy surfaces, or black backings. - **Use of Specific Tools**: UV lights designed for opal inspection can quickly identify phosphorescence to distinguish natural from synthetic opals.
### Summary Table for Differentiation
| Test/Feature | Natural Opal | Synthetic Opal | Doublets/Triplets | |-----------------------------|--------------------------------|-------------------------------|------------------------------------| | Formation | Natural, slow geological | Lab-grown, fast controlled | Composite with glued layers | | Phosphorescence (UV light) | Yes, glows after UV off | No phosphorescence | No phosphorescence | | Internal Pattern | Random, varied play of color | Mosaic, scale-like, "chicken wire" pattern | Flat separation lines visible | | Physical Feel | Smooth, glassy, natural feel | Sometimes plastic-like | Glassy capping, distinct backing | | Price & Value | High value, especially untreated | Lower value, ~10-20% of natural | Lowest resale value |
By combining these visual, physical, and luminescence tests, buyers can more confidently identify natural versus synthetic or composite opals and make informed purchasing decisions. Natural untreated opals hold higher value and long-term investment potential compared to synthetics or composites.
Despite misgivings about opals bringing bad luck, they are enjoying a resurgence in popularity. Synthetic opals, first created by Pierre Gilson in 1974, closely resemble natural opals but are not identical. It's crucial to distinguish between synthetic and natural opals when purchasing.
In the 18th and 19th centuries, perceptions of opals changed, and they were considered unlucky and a cause of misfortune. However, the allure of these iridescent gemstones has endured, and they continue to captivate jewellery lovers worldwide.
When storing opals, it's best to keep them in a cooler temperature with a bit of moisture in the air. Natural opals with play-of-colour have irregular patches of rainbow hues that flash at various levels within the stone. There are two main types of opals: precious (with play-of-color) and common (without play-of-color).
Highly valuable opals were discovered in the late 19th century in Australia, in deposits like Lightning Ridge and White Cliffs in New South Wales. For those born in October, opals can be considered a bit of gemstone magic to be enjoyed for their stunning play-of-colour unmatched by any other gemstone.
Precious opals were relatively rare before the 19th century, with the best examples coming from present-day Slovakia. Queen Alexandra, a successor to Queen Victoria, replaced precious opals in a tiara with rubies due to superstition. Common opals can come in various colors like pink, green, blue, or yellow.
Opals have been valued since ancient times, before Greek and Roman periods. Romans thought opals represented purity and hope, while Greeks believed they granted prophecy and foresight. Today, opals are more suited for earring and necklace settings rather than rings to keep them safe while wearing.
Sources: [1] https://www.gia.edu/opal-synthetic-vs-natural [2] https://www.gia.edu/opal-value [3] https://www.gia.edu/opal-phosphorescence [4] https://www.gia.edu/opal-types [5] https://www.gia.edu/opal-doublets-and-triplets
*In the realm of gemmology, understanding the differences between natural and lab-grown opals is essential for discerning their value and authenticity.* Those interested in the world of gemstones might find courses, workshops, or publications on opals beneficial to enhance their knowledge.* While shopping for opals, fashion-and-beauty enthusiasts can incorporate these unique stones into their jewelry collections, adding a touch of luxury to their lifestyle.* Home-and-garden enthusiasts could display opals as decorative elements, showcasing their beauty in vases or even using them as unusual coasters.* Travelers venturing to countries like Australia, Ethiopia, or Slovakia might be able to purchase natural opals directly from local markets or shops, providing an opportunity for personalized purchases.* Car aficionados, investors, or those seeking unique gifts might consider a rare, one-of-a-kind opal to add to their collection or to gift someone special.* For those with pets, caution should be exercised when keeping opals around curious animals that may try to knock them over or ingest them, as opals can be hazardous.* Lastly, opals can be fascinating subjects of research and study, with publications available on their history, care, and differentiation between natural and synthetic varieties—a educational pursuit for relationships that value knowledge and lifelong learning.
